Or what about something like this?
Would that work better than a bead of vulkem? See how I did it, in detail, on my blog. Tomorrow I fill the hole on the backside. That will be even more fun than doing the front side.

Not quite what I was expecting when I clicked on this thread, but I actually have a similar problem. I don't think anyone was locked out, I believe your trailer had a "travel latch" on the door, which is just a non-lockable knob on both sides. Mine has one that doesn't work (no doubt because my axles are shot ), and I've been looking for a deadbolt to replace it with. Unfortunately I can't find one that has the right backset and thickness, and because I DON'T want to drill that hole, I'm just living with it for the time being. Nice job on the star though!

Hey Frank, a question- where is the battery on your trailer? Mine has the same funky little compartment up front that is about 4.5" wide and aside from maybe a motorcycle battery, nothing fits the darn thing. Did you find something to fit or did you relocate yours?